The present invention relates to an apparatus in which picture signals or various kinds of digital signals are recorded and reproduced in and from a rotating flexible magnetic sheet through a magnetic head which is held in contact with the rotating magnetic sheet.
In the rotary magnetic sheet apparatus of the kind described, it is quite important to maintain a good contact between the magnetic sheet and the magnetic head, in order to attain a highly stable and reliable recording and reproduction of picture signals and various kinds of digital signals.
In order to meet this requirement, hitherto, an apparatus has been proposed in which, as shown in FIG. 1, a pad 5 is disposed facing a magnetic sheet 4 so that a rotating magnetic sheet 3 runs through a gap formed between the magnetic head 4 and the pad 5, thereby attaining a stable contact between the magnetic head 4 and the magnetic sheet 3. The pad 5 is provided with, for example, a head receiving recess 5a and the surface of the pad 5 facing the magnetic head 4 is covered by a buffer member 6. As shown in FIG. 3, the magnetic head projects into the recess 5a by a distance of a suitable amount to cause a slight deflection of the magnetic sheet 3 interposed therebetween, so that the magnetic sheet 3 makes contact with the magnetic head 4 with a moderate contact pressure due to its resilient force.
This prior arrangement, however, unavoidably suffers from the following disadvantages.
When the magnetic head 4 is held in contact with an outer peripheral portion of the magnetic sheet 3 for recording or reproduction, the contact cannot be maintained stably due to insufficient contact pressure because the outer peripheral portion of the magnetic sheet 3 is spaced from the sheet support 2a on a hub 2 to have a greater flexture as compared with the inner peripheral portion thereof.
Furthermore, it is to be noted also that, when the magnetic head 4 is positioned on the side of an outer peripheral portion of the magnetic sheet 3 as shown in FIG. 4, the pressing force of the outer peripheral portion of the magnetic sheet 3 exerted on the magnetic head 4 is reduced, so that the magnetic sheet 3 is contacted only by a portion of the surface of the magnetic head 4, as will be seen from FIG. 5.
In addition, the prior apparatus has the following disadvantage. The condition of contact between the magnetic sheet 3 and the magentic head 4 is influenced greatly by the shape of the pad 5 and by the gap between the magnetic head 4 and the pad 5. Accordingly, in order to establish a good condition of contact between the magnetic sheet 3 and magnetic head 4, it is essential to maintain a high accuracy with respect to the shape of the pad 5 and the gap between the magnetic head 4 and the pad 5.
However, the buffer member 6 is susceptible to a change in its dimension under the influence of changes in temperature and humidity and abrasion produced by the contact thereof with the magnetic sheet 3. According, the dimension of the pad 5 and the gap between the magnetic head 4 and the pad 5 are liable to change. In consequence, the condition of contact between the magnetic sheet 3 and the magnetic head 4 are also liable to change, so that such apparatus has a low reliability.